Preclinical efficacy and biological effects of the oral proteasome inhibitor ixazomib in diffuse large B-cell lymphoma
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Wei Liu1,5, Juan Chen1, Archito T. Tamayo1, Changgeng Ruan5, Li Li1, Shouhao Zhou3, Chan Shen4, Ken H. Young1, Jason Westin2, Richard E. Davis2, Shimin Hu1, Leonard J. Medeiros1, Richard J. Ford1 and Lan V. Pham1
1Department of Hematopathology, The University of Texas MD Anderson Cancer Center, Houston, TX, United States
2Department of Lymphoma and Myeloma, The University of Texas MD Anderson Cancer Center, Houston, TX, United States
3Department of Biostatistics, The University of Texas MD Anderson Cancer Center, Houston, TX, United States
4Department of Health Services Research, The University of Texas MD Anderson Cancer Center, Houston, TX, United States
5Department of Pathology, First Affiliated Hospital of Soochow University, Suzhou, Jiangsu, China
Lan V. Pham, email: [email protected]
Keywords: proteasome inhibitor, refractory DLBCL, ixazomib, DNA damage response, CHK2
Received: March 22, 2017 Accepted: August 08, 2017 Published: August 21, 2017
Despite advances in deciphering the molecular pathogenesis of diffuse large B-cell lymphoma (DLBCL), patients with relapsed/refractory disease, particularly those with adverse genetic features (e.g., mutated p53 or double hit lymphoma (DHL)) have very poor prognoses, and effective therapies are lacking. In this study we examined the preclinical efficacy and associated biological effects of the first oral proteasome inhibitor, ixazomib, in DLBCL in vitro and in vivo models. We demonstrated that ixazomib exhibited anti-tumor activities in 28 representative DLBCL cell lines, 10 primary DLBCL samples, and a DHL xenotransplant mouse model, at clinically achievable drug concentrations. Ixazomib sensitivity in DLBCL cells is correlated with immunoproteasomal activity; stimulating lymphoma cells with interferon gamma induced immunoproteasome activity and sensitized these cells to ixazomib. In addition, we showed that ixazomib induces apoptosis and the DNA damage response pathway, through activation of the checkpoint kinase 2 (CHK2). Hence, pharmacological inhibition of CHK2 enhances the anti-tumor activity of ixazomib in DLBCL cells. Our results indicate that ixazomib is an effective proteasome inhibitor active in DLBCL, including DHL, and its combination with a CHK2 inhibitor offers a potentially more robust therapeutic regimen for treatment-resistant DLBCL.
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